This scraper’s datastore

1.30pm (10.30pm JST): Good afternoon, welcome to the Guardian's live coverage of the Japanese humanitarian crisis and latest updates on conditions at the Fukushima Daiichi nuclear power plant. Here's a summary of the days events so far:

2011-03-16 20:17:27

You can read our previous live blog following Wednesday's developments here.

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• Authorities are struggling to control the situation at the Fukushima Daiichi nuclear plant, where the situation in reactors No 3 and No 4 remains fast-moving and perilous.Reactor 3 is a particular worry – Japan's government said today that there a "possibility" that the reactor's primary containment vessel for radiation had been damaged after steam was seen rising into the air. Attempts to drop water from helicopters was abandoned due to radiation levels. The latest mooted plan involves a police water cannon truck.Staff dousing reactors with seawater were forced to evacuate part of the building for a period this morning after radiation levels surged. These later receded and staff returned.French government ministers have urged the country's nationals in Tokyo to leave Japan or else head south in case radiation is blown onto the capital, saying Japanese authorities had "visibly lost control".

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• The country faces an increasingly desperate humanitarian crisis caused by the direct effects of Friday's huge earthquake and resultant tsunami, one made worse by freezing weather.The official death toll has now hit 4,255 deaths, with 8,194 people registered as unaccounted for. Survivors, many of them homeless, are struggling with a wave of cold weather forecast to last well into this week, with night time temperatures dipping to -5C in some places.

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• Japan's emperor, Akihito, has made a rare TV appearance to express his condolences to his people and his worry at the nuclear situation.• Following its precipitous plunge yesterday, Tokyo's stock market bounced back nearly 6%. Japan's central bank has injected a further $40bn into the financial markets.

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1.41pm (10.41pm JST: Ian Sample, the Guardian's science correspondent, has been talking to Andrew Sherry, director of the Dalton Nuclear Institute at Manchester University, about steam seen rising from the reactor 3. Ian says the fact steam is escaping does not necessarily mean any of the "serious containment structures" within reactor 3 have been damaged:

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1.46pm (10.46pm JST: My colleague Martin Shuttleworth has updated the Guardian's before and after pictures showing the devastation caused by the Japanese tsunami.

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The images show a lot of is yet to recede from the worst hit areas.

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1.58pm (10.58pm JST): James Randerson has sent through some more interesting nuclear context, from the UK's Institution of Mechanical Engineers. He particularly highlights this snippet:

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2.23pm (11.23pm JST): The New York Times has gone big today on comments by Yukio Edano, variously described as the chief cabinet secretary or the government's chief spokesman, that a cloud of steam rising from the No 3 reactor at the Fukushima nuclear plant indicated that the reactor's containment vessel, designed to keep in radiation, might have been ruptured. At a subsequent press conference he said that there was little chance of serious damage. But as the NYT notes, the "rapid and at times confusing pronouncements" by Japan's government are far from reassuring.

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2.31pm (11.31pm JST): It seems that a small number of people are benefiting from the nuclear scare: Adam Gabbatt reports here how sales of potassium iodide supplements, intended to limit the risk from radiation, have soared in the US and Canada.

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2.45pm (11.45pm BST): A man from the University of Canterbury in New Zealand who put together an interactive map of the various tremors which hit Christchurch has done the same for Japan (see screengrab below). It's fascinating – and frightening – to watch the sheer number of aftershocks.

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2.51pm (11.51pm JST): The main focus on this new blog so far has been on the nuclear situation, which is in some ways understandable as it's the most fast-moving and unpredictable element of the story, four days after the main quake and tsunami. But it's worth reiterating – as I tried to in this morning's blog – that a far greater humanitarian crisis remains.

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As well as an official death toll now over 4,200, which will inevitably rise much higher, hundreds of thousands of people have been left homeless, in many cases losing just about every possession. Their plight has been made worse by the severe weather affecting much of Japan's north-east at the moment, with some areas experiencing blizzards and temperatures of -5C. There are temporary evacuation shelters but these are generally basic and often very chilly. Food and fuel are in short supply.

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As we reach midnight in Japan it's perhaps worth looking through today's photo gallery of the quake aftermath and reflecting that worries about Chernobyl-style clouds of radioactivity sweeping across the Pacific, while understandable, are not the only issue.

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3.20pm (12.20am JST): John Vidal reports that David Cameron has said nuclear power should remain part of the UK's energy mix, while stressing there were lessons to be learned from the Japanese nuclear crisis.

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"I do think that nuclear power should be part of the mix in future as it is part of the mix right now," Cameron told parliament.

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"Obviously I'm sure that everyone watching the dreadful events in Japan will want to make sure we learn any lessons."

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Cameron's comments have provoked an immediate response from environment groups, John says. Here's a statement from Friends of the Earth:

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3.34pm (12.34am JST): Japanese authorities have "reported concerns" about the condition of the spent nuclear fuel pool at Fukushima Daiichi Unit 3 and Unit 4, the International Atomic Energy Agency has said.

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The IAEA quote above is already a little out of date – while Japan had indeed planned to use helicopters, we heard earlier that this plan had to be abandoned due to radiation levels.

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With the helicopters abandoned, plans are apparently now reliant on water cannon being deployed from ground level.

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3.44pm (12.44am JST): Right on cue, Kyodo news is reporting that a "water cannon vehicle" has arrived at reactor 4.

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3.49pm (12.49am JST): Suzy Goldenberg has just been on a conference call with US energy secretary and Nobel prize winner (in atomic physics) Stephen Chu. Suzy was tweeting as Chu spoke – here's a sample:

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• @suzyji Chu - There are several reactors now at risk. We do not want to speculate as to what will happen #eg

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• @suzyji Chu - We think there is a partial meltdown in #Japan, but doesn't mean containment vessel will fail #eg

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3.55pm (12.55am JST): Reuters is reporting that the head of the International Atomic Energy Agency has said the situation at the Fukushima Daiichi nuclear power plant is "very serious".

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4.03pm (1.03am JST): "The magnitude of the Japanese earthquakes and the main resulting tsunami are apparent from the immense scale of devastation and from the fact that all countries around the Pacific were affected," says Dr Philippe Blondel, deputy director of the Centre for Space, Atmospheric & Oceanic Science at University of Bath.

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Blondel adds that the "current fears about nuclear safety should not shadow the huge plight of the refugees":

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4.13pm (1.13am JST): The US is to fly a spy plane over the stricken Fukushima plant in a bid to get a closer look at the damage, according to Kyodo news.

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The Japanese news agency said the military will operate an unmanned Global Hawk high-altitude reconnaissance aircraft over the plant, perhaps as soon as Thursday, to examine the plant's reactors, Kyodo said, quoting a government source.

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"Photographs taken by the plane equipped with infrared sensors could provide a useful clue to what is occurring inside the reactor buildings, around which high-level radiation has been detected," it added.

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4.21pm (1.21am JST): The director general of the International Atomic Energy Agency, Yukiya Amano, has said he will travel to Japan as soon as possible, perhaps arriving as soon as Thursday.

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Amano, who is from Japan originally, will meet with senior officials and stay one night, he told reporters this afternoon. He said he hopes to come back with "firsthand information" on the situation and address the issue of improving the flow of information to the IAEA.

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Earlier today Amano urged the Japanese government to provide better information to the agency about the nuclear crisis.

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4.58pm (1.58am JST): Australia has advised its citizens to consider leaving Tokyo and earthquake-affected areas, but has said its advice is not due to the threat of nuclear contamination.

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The country's Department of Foreign Affairs and Trade said its advice to Australians had nothing to do with the threat from the damaged plant.

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"We are providing this advice because of the continuing disruption to major infrastructure, its impact on the welfare of people on the ground and continuing aftershocks," its notice said.

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5.36pm: Reuters reports that the US government is now advising its citizens who live within 80km of the Fukushima nuclear plant evacuate or take shelter indoors. The Japanese government has not altered its 20km exclusion zone.

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6pm: It's 3am JST in Japan, here's a summary of events today so far:

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• Tens of thousands of people are still missing since Friday's earthquake and tsunami. Around 850,000 households in the north of the country are still without power in near-freezing weather conditions, and water supplies are disrupted in the worst hit areas. The official death toll has reached 4,000 but the total number of dead is expected to exceed 10,000.

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• A massive international rescue effort to help Japan find and aid survivors is gathering pace. Japan's foreign ministry said today that 113 countries and regions as well as 24 international organisations had offered help, as well as offering assistance to tackle the deepening crisis at the Fukushima nuclear site.

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• Yukiya Amano, the head of the International Atomic Energy Agency, said the situation at the Fukushima Daiichi nuclear power plant is "very serious" and confirmed core damage at reactors 1, 2 and 3. Amano is to visit Japan as early as Thursday.

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• Earlier on Wednesday, a fire broke out at reactor No 4, a day after a blast blew a hole in the building housing the reactor's spent fuel rods. White smoke seen from No 3 reactor – thought to be most at risk – is most likely to be steam from water being poured in to cool exposed fuel rods.

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• Japanese authorities are resorting to desperate measures to cool down the damaged reactors. Plans for military helicopters to pour water onto a damaged reactor are being reconsidered, after an earlier attempt was aborted due to safety concerns. Police will attempt to add coolant to the No 4 reactor's spent fuel pool using a water cannon.

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• Japan's government says radiation levels around the Daiichi site are not at levels to cause an immediate health risk, while the Japanese Red Cross says Tokyo is safe for international travellers. The World Health Organisation says there is no evidence of a significant spread of radiation from the crippled Fukushima plant.

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• In a rare bright spot, the Nikkei share index gained 4.5% during trading on Wednesday as several major companies announced plans to reopen businesses. The country's central bank, the Bank of Japan, continued to inject trillions of yen to keep the economy functioning.

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This is Richard Adams in the Guardian's Washington bureau taking over live blogging duties.

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6.20pm: Tepco, the operator of the Fukushima Daiichi plant, is holding a press briefing and saying that a new power line that could solve the cooling problem at the plant is almost ready.

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No details yet but presumably that could mean the company could reconnect the reactors to the grip and so operate their usual cooling functions. Let's wait and see.

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6.33pm: The UK's Foreign Office is now advising that British nationals currently in Tokyo and to the north of Tokyo should consider leaving the area:

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More FCO information here.

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6.48pm: Some more details on the new power lines being laid to the Fukushima plant, from the Associated Press:

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7pm: The latest estimates from Japan's National Police Agency puts the tally of dead and missing at 12,000, with the death toll to date above 4,000.

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According to a statement by the agency:

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7.15pm: Tepco's delay in reconnecting the Fukushima plant to Japan's national grid is the subject of criticism from outside experts, writes my colleague Suzanne Goldenberg:

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7.30pm: AP is reporting a very worrying comment by Greg Jaczko, chairman of the US Nuclear Regulatory Commission:

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That presumably refers to No 4 reactor. Jaczko is currently giving a briefing on the nuclear plant crisis in Japan to the US Senate's committee on the environment and public works. (There's a live webcast of the briefing here.)

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If Jaczko's statement is correct, then there is nothing to stop the exposed fuel rods from getting hotter and melting down. And Jaczko should know: the NRC has experts on the ground in Japan.

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7.49pm: Jaczko's worrying comments below (see 7.30pm) are at odds with reports from the Japanese media saying that coolant continues to be added into the Fukushima reactors.

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According to the last report from the Jiji Press agency, posted nearly three hours ago, states:

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On the other hand, the discrepancy between the US and official Japanese position might explain why the US has told its citizens to maintain a 50 mile (80km) exclusion zone around Fukushima, compared with the 20 mile (30km) zone imposed by the Japanese government

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8pm: According to the Kyodo news agency, Japan's nuclear agency has said that the water level has been dropping in the No 5 reactor as well:

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Given what has happened elsewhere this isn't a surprise and we should expect the same thing in No 6 as well. Reactors 4, 5 and 6 were actually out of commission at the time of the earthquake and tsunami, but the danger remains because of the highly radioactive used fuel stored in the reactors. In the case of No 4, it may have had more spent fuel, and it was harmed by the nearby explosions in the 1, 2 and 3 reactors, which was most likely to cause of the first fire in No 4.

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8.21pm: More on the comments on the Fukushima nuclear plant by Greg Jaczko, chairman of the US Nuclear Regulatory Commission, to a congressional committee in Washington:

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Jaczko also said there was the possibility of a leak in the spent fuel pool in reactor No 3, "which could lead to a loss of water in that pool", as well as a falling water level in the spent fuel level at the No 2 reactor.

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According to Reuters, Jaczko said radiation levels around the site could give emergency workers "lethal doses" of radiation, forcing them to stay away:

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8.40pm: Fukushima cannot possibly become a second Chernobyl disaster, explains Sir John Beddington, the UK's chief scientific officer, speaking to the British embassy in Tokyo:

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9pm: Facebook user Jun Shiomitsu has been collating and translating into English Japanese Twitter messages sent out about people's experiences following last week's earthquake. You can read them on his Facebook page but here are a few translations:

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9.14pm: Japanese authorities have denied the claim by Greg Jaczko, chairman of the US Nuclear Regulatory Commission, that the No 4 reactor at Fukushima may have lost all its coolant.

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AP reports Hajime Motojuku, spokesman for plant operator Tepco, as saying the "condition is stable" at the No 4 reactor.

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9.29pm: A useful post from the journal Nature explaining the types of radiation and their effects, to help readers know their millisieverts from their microsieverts:

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9.51pm: The Guardian's Jon Watts is in Kitakami, Iwate Prefecture, finds that many of those hit by the disaster still lack blankets, food or fuel, raising fears of a full-blown humanitarian crisis:

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10.10pm: Nuclear plant operator Tepco says it plans to try again on Thursday with its plan to drop water into the No 3 reactor by military helicopter. The frist attempt today was called off because of high radiation around the Fukushima Daiichi site, although the IAEA also had concerns about the method.

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The damaged No 3 reactor remains the highest priority, because of the presence of Mox (Mixed oxide) fuel which contains highly dangerous plutonium.

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10.24pm: Japan's giant car manufacturers remain closed in the wake of the traumatic earthquake and tsunami – but there was a sliver of good news from Toyota.

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The company said it will keep its car production lines closed for another week, but said it will reopen its replacement parts factories on Thursday and the factories making parts for overseas production on Monday.

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Nissan also said it is restarting car assembly on Thursday for as long as supplies lasts.

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10.39pm: Greg Jaczko of the US Nuclear Regulatory Commission was buttonholed by journalists in Congress and pressed on his claims of no water remaining in a No 4 reactor's spent fuel pool, subsequently denied by Japanese officials. Jaczko says:

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The NRC has 11 staff currently working in Japan. Jaczko did also say: "It is my great hope that the information is not accurate."

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10.54pm: NHK has more details on Tepco's attempts to lay new power lines to the Fukushima Daiichi nuclear plant and restart cooling systems:

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11.08pm: Asahi Shimbun's English language site on Facebook has a description of the grim conditions facing refugees in the icy north of Japan, at the centre of the earthquake's devastation:

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11.22pm: The New York Times gives its take on the differing Japanese and American views on the facts inside the Fukushima reactors:

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11.45pm: The Japanese yen has strengthened remarkably against the US dollar and other currencies such as the Australian dollar in overnight foreign exchange trading.

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The yen now stands at its highest level against the US dollar since 1945, with just over 76 yen to the dollar, on a wave of buying in anticipation of Japanese companies selling dollar-denominated assets and moving funds back into yen.

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The strengthening yen helped push Japanese share prices down, with the stronger yen making Japan's exports more expensive. The government may intervene in the foreign exchange market and sell yen to push its value down.

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Meanwhile, the Bank of Japan injected trillions of yen in the country's financial system for the fourth day in a row.

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12.17am: Kyodo news agency is reporting that Japanese Self-Defense Forces helicopters are in the air monitoring radiation levels above the Fukushima Daiichi reactor.

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12.28am: The International Atomic Energy Agency has more bad news that temperatures within Fukushima Daiichi reactors number 4, 5 and 6 have been rising.

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Until today there had been little to say about the 5 and 6 reactors, which along with reactor No 4 had been shut down at the time of the earthquake. But all three contain spent fuel.

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12.42am: The search for bodies continues along Japan's northeast coast as survivors and rescue teams hunt for the missing. This AP story is filed from Miyagi prefecture:

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1am: Broadcaster NHK is reporting that water tankers are near the Fukushima power plant, preparing to spray water into the No 4 reactor:

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1.14am: The Guardian's Suzanne Goldenberg looks at criticism of how Japan authorities have tackled the nuclear crisis emerging at Fukushima – and talks to the man who had to clean up Chernobyl, who has a chilling logic:

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Further down:

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1.26am: Reuters has a round-up of the aftermath of Japan's earthquake disaster in numbers:

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The death toll is expected to exceed 10,000, with northeastern prefectures of Miyagi, Iwate and Fukushima most severely hit. At least 4,314 people were confirmed dead, but more than 8,600 people are still missing, Japan's Asahi newspaper quoted police as saying on early Thursday.

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More than 440,000 people have been evacuated, NHK says. Hundreds of people are waiting for help in isolated areas and have no access to food.

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About 850,000 households in the north are still without electricity in near-freezing weather, Tohuku Electric Power Company says. The government says at least 1.5m households lack running water.

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More than 100,000 buildings have been damaged, including at least 7,400 completely destroyed, public broadcaster NHK says.